Monitoring Services

Ceph Dashboard uses Prometheus, Grafana, and related tools to store and visualize detailed metrics on cluster utilization and performance. Ceph users have three options:

  1. Have cephadm deploy and configure these services. This is the default when bootstrapping a new cluster unless the --skip-monitoring-stack option is used.

  2. Deploy and configure these services manually. This is recommended for users with existing prometheus services in their environment (and in cases where Ceph is running in Kubernetes with Rook).

  3. Skip the monitoring stack completely. Some Ceph dashboard graphs will not be available.

The monitoring stack consists of Prometheus, Prometheus exporters (Prometheus Module, Node exporter), Prometheus Alert Manager and Grafana.

Note

Prometheus’ security model presumes that untrusted users have access to the Prometheus HTTP endpoint and logs. Untrusted users have access to all the (meta)data Prometheus collects that is contained in the database, plus a variety of operational and debugging information.

However, Prometheus’ HTTP API is limited to read-only operations. Configurations can not be changed using the API and secrets are not exposed. Moreover, Prometheus has some built-in measures to mitigate the impact of denial of service attacks.

Please see Prometheus’ Security model <https://prometheus.io/docs/operating/security/> for more detailed information.

Deploying monitoring with cephadm

The default behavior of cephadm is to deploy a basic monitoring stack. It is however possible that you have a Ceph cluster without a monitoring stack, and you would like to add a monitoring stack to it. (Here are some ways that you might have come to have a Ceph cluster without a monitoring stack: You might have passed the --skip-monitoring stack option to cephadm during the installation of the cluster, or you might have converted an existing cluster (which had no monitoring stack) to cephadm management.)

To set up monitoring on a Ceph cluster that has no monitoring, follow the steps below:

  1. Deploy a node-exporter service on every node of the cluster. The node-exporter provides host-level metrics like CPU and memory utilization:

    ceph orch apply node-exporter

  2. Deploy alertmanager:

    ceph orch apply alertmanager

  3. Deploy Prometheus. A single Prometheus instance is sufficient, but for high availablility (HA) you might want to deploy two:

    ceph orch apply prometheus

    or

    ceph orch apply prometheus --placement 'count:2'

  4. Deploy grafana:

    ceph orch apply grafana

Centralized Logging in Ceph

Ceph now provides centralized logging with Loki & Promtail. Centralized Log Management (CLM) consolidates all log data and pushes it to a central repository, with an accessible and easy-to-use interface. Centralized logging is designed to make your life easier. Some of the advantages are:

  1. Linear event timeline: it is easier to troubleshoot issues analyzing a single chain of events than thousands of different logs from a hundred nodes.

  2. Real-time live log monitoring: it is impractical to follow logs from thousands of different sources.

  3. Flexible retention policies: with per-daemon logs, log rotation is usually set to a short interval (1-2 weeks) to save disk usage.

  4. Increased security & backup: logs can contain sensitive information and expose usage patterns. Additionally, centralized logging allows for HA, etc.

Centralized Logging in Ceph is implemented using two new services - loki & promtail.

Loki: It is basically a log aggregation system and is used to query logs. It can be configured as a datasource in Grafana.

Promtail: It acts as an agent that gathers logs from the system and makes them available to Loki.

These two services are not deployed by default in a Ceph cluster. To enable the centralized logging you can follow the steps mentioned here Enable Centralized Logging in Dashboard.

Networks and Ports

All monitoring services can have the network and port they bind to configured with a yaml service specification

example spec file:

service_type: grafana
service_name: grafana
placement:
  count: 1
networks:
- 192.169.142.0/24
spec:
  port: 4200

Using custom images

It is possible to install or upgrade monitoring components based on other images. To do so, the name of the image to be used needs to be stored in the configuration first. The following configuration options are available.

  • container_image_prometheus

  • container_image_grafana

  • container_image_alertmanager

  • container_image_node_exporter

Custom images can be set with the ceph config command

ceph config set mgr mgr/cephadm/<option_name> <value>

For example

ceph config set mgr mgr/cephadm/container_image_prometheus prom/prometheus:v1.4.1

If there were already running monitoring stack daemon(s) of the type whose image you’ve changed, you must redeploy the daemon(s) in order to have them actually use the new image.

For example, if you had changed the prometheus image

ceph orch redeploy prometheus

Note

By setting a custom image, the default value will be overridden (but not overwritten). The default value changes when updates become available. By setting a custom image, you will not be able to update the component you have set the custom image for automatically. You will need to manually update the configuration (image name and tag) to be able to install updates.

If you choose to go with the recommendations instead, you can reset the custom image you have set before. After that, the default value will be used again. Use ceph config rm to reset the configuration option

ceph config rm mgr mgr/cephadm/<option_name>

For example

ceph config rm mgr mgr/cephadm/container_image_prometheus

See also Deployment in an isolated environment.

Using custom configuration files

By overriding cephadm templates, it is possible to completely customize the configuration files for monitoring services.

Internally, cephadm already uses Jinja2 templates to generate the configuration files for all monitoring components. Starting from version 17.2.3, cephadm supports Prometheus http service discovery, and uses this endpoint for the definition and management of the embedded Prometheus service. The endpoint listens on https://<mgr-ip>:8765/sd/ (the port is configurable through the variable service_discovery_port) and returns scrape target information in http_sd_config format

Customers with external monitoring stack can use ceph-mgr service discovery endpoint to get scraping configuration. Root certificate of the server can be obtained by the following command:

ceph orch sd dump cert

The configuration of Prometheus, Grafana, or Alertmanager may be customized by storing a Jinja2 template for each service. This template will be evaluated every time a service of that kind is deployed or reconfigured. That way, the custom configuration is preserved and automatically applied on future deployments of these services.

Note

The configuration of the custom template is also preserved when the default configuration of cephadm changes. If the updated configuration is to be used, the custom template needs to be migrated manually after each upgrade of Ceph.

Option names

The following templates for files that will be generated by cephadm can be overridden. These are the names to be used when storing with ceph config-key set:

  • services/alertmanager/alertmanager.yml

  • services/grafana/ceph-dashboard.yml

  • services/grafana/grafana.ini

  • services/prometheus/prometheus.yml

  • services/prometheus/alerting/custom_alerts.yml

You can look up the file templates that are currently used by cephadm in src/pybind/mgr/cephadm/templates:

  • services/alertmanager/alertmanager.yml.j2

  • services/grafana/ceph-dashboard.yml.j2

  • services/grafana/grafana.ini.j2

  • services/prometheus/prometheus.yml.j2

Usage

The following command applies a single line value:

ceph config-key set mgr/cephadm/<option_name> <value>

To set contents of files as template use the -i argument:

ceph config-key set mgr/cephadm/<option_name> -i $PWD/<filename>

Note

When using files as input to config-key an absolute path to the file must be used.

Then the configuration file for the service needs to be recreated. This is done using reconfig. For more details see the following example.

Example

# set the contents of ./prometheus.yml.j2 as template
ceph config-key set mgr/cephadm/services/prometheus/prometheus.yml \
  -i $PWD/prometheus.yml.j2

# reconfig the prometheus service
ceph orch reconfig prometheus

# set additional custom alerting rules for Prometheus
ceph config-key set mgr/cephadm/services/prometheus/alerting/custom_alerts.yml \
  -i $PWD/custom_alerts.yml

# Note that custom alerting rules are not parsed by Jinja and hence escaping
# will not be an issue.

Deploying monitoring without cephadm

If you have an existing prometheus monitoring infrastructure, or would like to manage it yourself, you need to configure it to integrate with your Ceph cluster.

  • Enable the prometheus module in the ceph-mgr daemon

    ceph mgr module enable prometheus

    By default, ceph-mgr presents prometheus metrics on port 9283 on each host running a ceph-mgr daemon. Configure prometheus to scrape these.

To make this integration easier, cephadm provides a service discovery endpoint at https://<mgr-ip>:8765/sd/. This endpoint can be used by an external Prometheus server to retrieve target information for a specific service. Information returned by this endpoint uses the format specified by the Prometheus http_sd_config option

Here’s an example prometheus job definition that uses the cephadm service discovery endpoint

- job_name: 'ceph-exporter'
  http_sd_configs:
  - url: http://<mgr-ip>:8765/sd/prometheus/sd-config?service=ceph-exporter

Disabling monitoring

To disable monitoring and remove the software that supports it, run the following commands:

$ ceph orch rm grafana
$ ceph orch rm prometheus --force   # this will delete metrics data collected so far
$ ceph orch rm node-exporter
$ ceph orch rm alertmanager
$ ceph mgr module disable prometheus

See also Removing a Service.

Setting up RBD-Image monitoring

Due to performance reasons, monitoring of RBD images is disabled by default. For more information please see Ceph Health Checks. If disabled, the overview and details dashboards will stay empty in Grafana and the metrics will not be visible in Prometheus.

Setting up Prometheus

Setting Prometheus Retention Size and Time

Cephadm can configure Prometheus TSDB retention by specifying retention_time and retention_size values in the Prometheus service spec. The retention time value defaults to 15 days (15d). Users can set a different value/unit where supported units are: ‘y’, ‘w’, ‘d’, ‘h’, ‘m’ and ‘s’. The retention size value defaults to 0 (disabled). Supported units in this case are: ‘B’, ‘KB’, ‘MB’, ‘GB’, ‘TB’, ‘PB’ and ‘EB’.

In the following example spec we set the retention time to 1 year and the size to 1GB.

service_type: prometheus
placement:
  count: 1
spec:
  retention_time: "1y"
  retention_size: "1GB"

Note

If you already had Prometheus daemon(s) deployed before and are updating an existent spec as opposed to doing a fresh Prometheus deployment, you must also tell cephadm to redeploy the Prometheus daemon(s) to put this change into effect. This can be done with a ceph orch redeploy prometheus command.

Setting up Grafana

Manually setting the Grafana URL

Cephadm automatically configures Prometheus, Grafana, and Alertmanager in all cases except one.

In a some setups, the Dashboard user’s browser might not be able to access the Grafana URL that is configured in Ceph Dashboard. This can happen when the cluster and the accessing user are in different DNS zones.

If this is the case, you can use a configuration option for Ceph Dashboard to set the URL that the user’s browser will use to access Grafana. This value will never be altered by cephadm. To set this configuration option, issue the following command:

ceph dashboard set-grafana-frontend-api-url <grafana-server-api>

It might take a minute or two for services to be deployed. After the services have been deployed, you should see something like this when you issue the command ceph orch ls:

$ ceph orch ls
NAME           RUNNING  REFRESHED  IMAGE NAME                                      IMAGE ID        SPEC
alertmanager       1/1  6s ago     docker.io/prom/alertmanager:latest              0881eb8f169f  present
crash              2/2  6s ago     docker.io/ceph/daemon-base:latest-master-devel  mix           present
grafana            1/1  0s ago     docker.io/pcuzner/ceph-grafana-el8:latest       f77afcf0bcf6   absent
node-exporter      2/2  6s ago     docker.io/prom/node-exporter:latest             e5a616e4b9cf  present
prometheus         1/1  6s ago     docker.io/prom/prometheus:latest                e935122ab143  present

Configuring SSL/TLS for Grafana

cephadm deploys Grafana using the certificate defined in the ceph key/value store. If no certificate is specified, cephadm generates a self-signed certificate during the deployment of the Grafana service.

A custom certificate can be configured using the following commands:

ceph config-key set mgr/cephadm/grafana_key -i $PWD/key.pem
ceph config-key set mgr/cephadm/grafana_crt -i $PWD/certificate.pem

If you have already deployed Grafana, run reconfig on the service to update its configuration:

ceph orch reconfig grafana

The reconfig command also sets the proper URL for Ceph Dashboard.

Setting the initial admin password

By default, Grafana will not create an initial admin user. In order to create the admin user, please create a file grafana.yaml with this content:

service_type: grafana
spec:
  initial_admin_password: mypassword

Then apply this specification:

ceph orch apply -i grafana.yaml
ceph orch redeploy grafana

Grafana will now create an admin user called admin with the given password.

Turning off anonymous access

By default, cephadm allows anonymous users (users who have not provided any login information) limited, viewer only access to the grafana dashboard. In order to set up grafana to only allow viewing from logged in users, you can set anonymous_access: False in your grafana spec.

service_type: grafana
placement:
  hosts:
  - host1
spec:
  anonymous_access: False
  initial_admin_password: "mypassword"

Since deploying grafana with anonymous access set to false without an initial admin password set would make the dashboard inaccessible, cephadm requires setting the initial_admin_password when anonymous_access is set to false.

Setting up Alertmanager

Adding Alertmanager webhooks

To add new webhooks to the Alertmanager configuration, add additional webhook urls like so:

service_type: alertmanager
spec:
  user_data:
    default_webhook_urls:
    - "https://foo"
    - "https://bar"

Where default_webhook_urls is a list of additional URLs that are added to the default receivers’ <webhook_configs> configuration.

Run reconfig on the service to update its configuration:

ceph orch reconfig alertmanager

Turn on Certificate Validation

If you are using certificates for alertmanager and want to make sure these certs are verified, you should set the “secure” option to true in your alertmanager spec (this defaults to false).

service_type: alertmanager
spec:
  secure: true

If you already had alertmanager daemons running before applying the spec you must reconfigure them to update their configuration

ceph orch reconfig alertmanager

Further Reading